DE 196 26 625 A1 discloses a device of this kind. It comprises a manually operable hand throttle ring mounted to be concentric with the circular steering wheel of a motor vehicle and having a smaller diameter than the steering wheel. The hand throttle ring is movable against the force exerted by energy storage means to act upon an actuating member. The actuating member moves a control rod mounted for axial movement inside the steering column of the motor vehicle. The control rod in turn actuates the conventional throttle pedal of the motor vehicle.
A device of this kind converts the stroke, or the depression distance, of the hand throttle ring into a movement of the throttle pedal to perform a predetermined stroke or amount of depression.
Conventionally, the stroke of a throttle pedal in a motor vehicle is about 60 mm average when actuated from idle to full throttle. In contrast, the stroke of a hand throttle ring is about 18 mm from idle to full throttle. What this means is that acceleration—especially on start-up and the concomitant actuation of the hand throttle ring—may result in a jerky and imprecise start-up process, which the driver and a passenger will find most unpleasant.